What causes a bungee cord to stretch?

A bungee cord stretches due to its elastic properties, which allow it to deform under tension. When a weight is applied, such as a person jumping off a platform, the force of gravity pulls the weight downward, causing the cord to extend. The material's elasticity enables it to return to its original shape once the force is removed, allowing for a safe rebound. This stretching and contracting mechanism is governed by Hooke's Law, which states that the force exerted by the cord is proportional to its extension.